/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.jca.context;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.StandardEnvironment;
import org.springframework.lang.Nullable;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;

import javax.resource.NotSupportedException;
import javax.resource.ResourceException;
import javax.resource.spi.ActivationSpec;
import javax.resource.spi.BootstrapContext;
import javax.resource.spi.ResourceAdapter;
import javax.resource.spi.ResourceAdapterInternalException;
import javax.resource.spi.endpoint.MessageEndpointFactory;
import javax.transaction.xa.XAResource;

/**
 * JCA 1.7 {@link javax.resource.spi.ResourceAdapter} implementation
 * that loads a Spring {@link org.springframework.context.ApplicationContext},
 * starting and stopping Spring-managed beans as part of the ResourceAdapter's
 * lifecycle.
 *
 * <p>Ideal for application contexts that do not need any HTTP entry points
 * but rather just consist of message endpoints and scheduled jobs etc.
 * Beans in such a context may use application server resources such as the
 * JTA transaction manager and JNDI-bound JDBC DataSources and JMS
 * ConnectionFactory instances, and may also register with the platform's
 * JMX server - all through Spring's standard transaction management and
 * JNDI and JMX support facilities.
 *
 * <p>If the need for scheduling asynchronous work arises, consider using
 * Spring's {@link org.springframework.jca.work.WorkManagerTaskExecutor}
 * as a standard bean definition, to be injected into application beans
 * through dependency injection. This WorkManagerTaskExecutor will automatically
 * use the JCA WorkManager from the BootstrapContext that has been provided
 * to this ResourceAdapter.
 *
 * <p>The JCA {@link javax.resource.spi.BootstrapContext} may also be
 * accessed directly, through application components that implement the
 * {@link BootstrapContextAware} interface. When deployed using this
 * ResourceAdapter, the BootstrapContext is guaranteed to be passed on
 * to such components.
 *
 * <p>This ResourceAdapter is to be defined in a "META-INF/ra.xml" file
 * within a Java EE ".rar" deployment unit like as follows:
 *
 * <pre class="code">
 * &lt;?xml version="1.0" encoding="UTF-8"?&gt;
 * &lt;connector xmlns="http://java.sun.com/xml/ns/j2ee"
 * 		 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 * 		 xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee https://java.sun.com/xml/ns/j2ee/connector_1_5.xsd"
 * 		 version="1.5"&gt;
 * 	 &lt;vendor-name&gt;Spring Framework&lt;/vendor-name&gt;
 * 	 &lt;eis-type&gt;Spring Connector&lt;/eis-type&gt;
 * 	 &lt;resourceadapter-version&gt;1.0&lt;/resourceadapter-version&gt;
 * 	 &lt;resourceadapter&gt;
 * 		 &lt;resourceadapter-class&gt;org.springframework.jca.context.SpringContextResourceAdapter&lt;/resourceadapter-class&gt;
 * 		 &lt;config-property&gt;
 * 			 &lt;config-property-name&gt;ContextConfigLocation&lt;/config-property-name&gt;
 * 			 &lt;config-property-type&gt;java.lang.String&lt;/config-property-type&gt;
 * 			 &lt;config-property-value&gt;META-INF/applicationContext.xml&lt;/config-property-value&gt;
 * 		 &lt;/config-property&gt;
 * 	 &lt;/resourceadapter&gt;
 * &lt;/connector&gt;</pre>
 * <p>
 * Note that "META-INF/applicationContext.xml" is the default context config
 * location, so it doesn't have to specified unless you intend to specify
 * different/additional config files. So in the default case, you may remove
 * the entire {@code config-property} section above.
 *
 * <p><b>For simple deployment needs, all you need to do is the following:</b>
 * Package all application classes into a RAR file (which is just a standard
 * JAR file with a different file extension), add all required library jars
 * into the root of the RAR archive, add a "META-INF/ra.xml" deployment
 * descriptor as shown above as well as the corresponding Spring XML bean
 * definition file(s) (typically "META-INF/applicationContext.xml"),
 * and drop the resulting RAR file into your application server's
 * deployment directory!
 *
 * @author Juergen Hoeller
 * @see #setContextConfigLocation
 * @see #loadBeanDefinitions
 * @see ResourceAdapterApplicationContext
 * @since 2.5
 */
public class SpringContextResourceAdapter implements ResourceAdapter {

    /**
     * Any number of these characters are considered delimiters between
     * multiple context config paths in a single String value.
     *
     * @see #setContextConfigLocation
     */
    public static final String CONFIG_LOCATION_DELIMITERS = ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS;

    /**
     * The default {@code applicationContext.xml} location.
     */
    public static final String DEFAULT_CONTEXT_CONFIG_LOCATION = "META-INF/applicationContext.xml";


    protected final Log logger = LogFactory.getLog(getClass());

    private String contextConfigLocation = DEFAULT_CONTEXT_CONFIG_LOCATION;

    @Nullable
    private ConfigurableApplicationContext applicationContext;

    /**
     * Return the specified context configuration files.
     */
    protected String getContextConfigLocation() {
        return this.contextConfigLocation;
    }

    /**
     * Set the location of the context configuration files, within the
     * resource adapter's deployment unit. This can be a delimited
     * String that consists of multiple resource location, separated
     * by commas, semicolons, whitespace, or line breaks.
     * <p>This can be specified as "ContextConfigLocation" config
     * property in the {@code ra.xml} deployment descriptor.
     * <p>The default is "classpath:META-INF/applicationContext.xml".
     */
    public void setContextConfigLocation(String contextConfigLocation) {
        this.contextConfigLocation = contextConfigLocation;
    }

    /**
     * Return a new {@link StandardEnvironment}.
     * <p>Subclasses may override this method in order to supply
     * a custom {@link ConfigurableEnvironment} implementation.
     */
    protected ConfigurableEnvironment createEnvironment() {
        return new StandardEnvironment();
    }

    /**
     * This implementation loads a Spring ApplicationContext through the
     * {@link #createApplicationContext} template method.
     */
    @Override
    public void start(BootstrapContext bootstrapContext) throws ResourceAdapterInternalException {
        if (logger.isDebugEnabled()) {
            logger.debug("Starting SpringContextResourceAdapter with BootstrapContext: " + bootstrapContext);
        }
        this.applicationContext = createApplicationContext(bootstrapContext);
    }

    /**
     * Build a Spring ApplicationContext for the given JCA BootstrapContext.
     * <p>The default implementation builds a {@link ResourceAdapterApplicationContext}
     * and delegates to {@link #loadBeanDefinitions} for actually parsing the
     * specified configuration files.
     *
     * @param bootstrapContext this ResourceAdapter's BootstrapContext
     * @return the Spring ApplicationContext instance
     */
    protected ConfigurableApplicationContext createApplicationContext(BootstrapContext bootstrapContext) {
        ResourceAdapterApplicationContext applicationContext =
                new ResourceAdapterApplicationContext(bootstrapContext);

        // Set ResourceAdapter's ClassLoader as bean class loader.
        applicationContext.setClassLoader(getClass().getClassLoader());

        // Extract individual config locations.
        String[] configLocations =
                StringUtils.tokenizeToStringArray(getContextConfigLocation(), CONFIG_LOCATION_DELIMITERS);

        loadBeanDefinitions(applicationContext, configLocations);
        applicationContext.refresh();

        return applicationContext;
    }

    /**
     * Load the bean definitions into the given registry,
     * based on the specified configuration files.
     *
     * @param registry        the registry to load into
     * @param configLocations the parsed config locations
     * @see #setContextConfigLocation
     */
    protected void loadBeanDefinitions(BeanDefinitionRegistry registry, String[] configLocations) {
        new XmlBeanDefinitionReader(registry).loadBeanDefinitions(configLocations);
    }

    /**
     * This implementation closes the Spring ApplicationContext.
     */
    @Override
    public void stop() {
        logger.debug("Stopping SpringContextResourceAdapter");
        if (this.applicationContext != null) {
            this.applicationContext.close();
        }
    }


    /**
     * This implementation always throws a NotSupportedException.
     */
    @Override
    public void endpointActivation(MessageEndpointFactory messageEndpointFactory, ActivationSpec activationSpec)
            throws ResourceException {

        throw new NotSupportedException("SpringContextResourceAdapter does not support message endpoints");
    }

    /**
     * This implementation does nothing.
     */
    @Override
    public void endpointDeactivation(MessageEndpointFactory messageEndpointFactory, ActivationSpec activationSpec) {
    }

    /**
     * This implementation always returns {@code null}.
     */
    @Override
    @Nullable
    public XAResource[] getXAResources(ActivationSpec[] activationSpecs) throws ResourceException {
        return null;
    }


    @Override
    public boolean equals(Object other) {
        return (this == other || (other instanceof SpringContextResourceAdapter &&
                ObjectUtils.nullSafeEquals(getContextConfigLocation(),
                        ((SpringContextResourceAdapter) other).getContextConfigLocation())));
    }

    @Override
    public int hashCode() {
        return ObjectUtils.nullSafeHashCode(getContextConfigLocation());
    }

}
